var lengthOfLongestSubstring = function(s) {
    let n = s.length;
    let sum = 1;
    if(n == 0) {
        return 0;
    }
    for(let i = 0; i < n; i++) {
        let l = i;
        let r = l;
         let m = new Set();
        while(r<n) {
            if(!m.has(s[r])) {
                m.add(s[r])
                sum = Math.max(sum, r-l+1)
                r++;
            } else {
                m = new Set();
                l = r;
                m.add(s[l])
                r++;
            }
        }
    }
    return sum;
};
console.log(lengthOfLongestSubstring('abcabcbb'))
let abc = '124 啊'
console.log(Number(abc), parseInt(abc))